Dietary iodine

About iodine

Iodine is a trace element that is essential to the functioning of our body. It plays a particularly important role in the production of vital thyroid hormones. Iodine is an element that is needed for the production of thyroid hormone. The body does not make iodine, so it is an essential part of your diet. A diet inadequate in iodine can result in deficiency and subsequent complications such as goiter and cretinism.

‘Iodine deficiency is the most common preventable cause of mental retardation in the world. Obtaining iodine through the food supply is therefore paramount.’ (1)

Why are we becoming deficient?

The onset of iodine deficiency within Australia can be largely attributed to the new sanitisation techniques employed by the dairy industry. Originally the sanitisers used during processing of dairy contained iodophors – this made dairy products a good source of iodine. However, the new methods do not provide the same amount of iodine.

Additionally, there has been a decline in the use of iodised salt due to the raised awareness of the link between salt and hypertension.

What does the thyroid do?

In short, the thyroid is responsible for the regulation of many metabolic processes. It controls the metabolic rate and hence the use of energy. The thyroid hormones work to promote healthy growth and development of the entire body. Without sufficient dietary iodine, the thyroid gland cannot create a sufficient quantity of thyroid hormones, this can lead to serious health complications.

Consequences of inadequate dietary iodine

Hypothyroidism

As the body’s iodine levels fall, there will be insufficient iodine available for the production of thyroid hormones by the thyroid gland.

In the long term…

Since iodine is essential for making thyroid hormones, hypothyroidism will develop if iodine deficiency is not corrected. This is basically where not enough thyroid hormones are being produced to meet the body’s needs. Whilst iodine deficiency is an uncommon cause for hypothyroidism in Australia, worldwide this is the number one cause.

Other consequences of inadequate dietary iodine may include:

Goiter

When we do not receive enough iodine through our diet, the thyroid gland can become enlarged. The thyroid gland does this in an attempt to compensate for the lack of iodine which is needed to produce thyroid hormones. This is condition is known as goiter. Patients with symptomatic goiter may require surgical removal of the thyroid gland (thyroidectomy).

Pregnancy-related problems

Iodine requirements are increased during pregnancy to ensure the normal development of the babies’ brain. It is therefore of particular importance that an iodine deficiency is not present in women who are pregnant or breastfeeding. During pregnancy, insufficient intake of iodine and even mild deficiency can result in delayed physical and mental development of your child including hearing and speech abnormalities. A sever deficiency in iodine has also been linked with an increased risk for miscarriage, preterm delivery and stillbirth. The most common preventable cause of mental retardation is congenital hypothyroidism. This is the case worldwide and it can be prevented by an adequate iodine intake.

Cretinism

An infant can suffer from cretinism if the mother was severely iodine deficient during pregnancy. The infant experiences severe mental and physical stunting due to an insufficiency of thyroid hormones to have supported successful development. Hearing complications and spasticity can also result.

Recommended daily intake of iodine

The recommended daily intake (RDI) for iodine will vary based on your age and life stage. In comparison to other nutrients, we only need a very small amount of iodine.

The requirements are measured in micrograms (µg) and are as follows:

younger children (1 to 8 years) – 90µg

older children (9 to 13 years, boys and girls) – 120µg

adolescents (14 to 18 years) – 150µg

men – 150µg

women – 150µg

during pregnancy and breastfeeding – 220µg and 270µg respectively

The above recommendations were taken from the Nutrient reference Values for Australia and New Zealand, developed by the National health and Medical Research Council. (2)

Food sources of iodine

Seafood

Seafood is a good source of iodine. This includes both fish, shellfish and even seaweed.

Bread

It is now compulsory (as of 2009) for manufacturers to fortify their bread with iodine. This is achieved through the substitution of regular salt for iodised salt.

Salt

I don’t want to encourage anyone to get in to the habit of using salt. If you already do however, make the swap to iodised salt.

Good sources of iodine

Table sourced from Nutrition Australia (1)

Contact us for results focused nutritional advice

This article was written by our dietitian Belinda Elwin who is a Dietitians Association of Australia member and Accredited Practising Dietitian and Nutritionist.

If you have questions about dietary iodine or other nutrition related issues, make an appointment. We‘ll provide you with a simple and effective routine targeted to your concerns. Contact us today.

References

About Belinda Elwin

Belinda is a fully Accredited Practicing Dietitian and Nutritionist who has experience working with both children and adults. She is constantly ensuring her knowledge is up to date by attending conferences, workshops and keeping on top of newly emerging evidence.

Belinda has worked within the community by conducting supermarket tours and regularly delivering presentations to schools and support groups. Additionally, she leads a healthy lifestyle program for children outside of the healthy weight range. During the week, she also works with inpatients in the public hospital system.

Belinda combines her experience and skill set to provide practical, client specific advice through dietary counselling. In particular, Belinda has a broad range of experience with weight management, diabetes, oncology, high cholesterol, malnutrition, childhood nutrition and gastrointestinal disorders. She is passionate about her career and helping others to improve their quality of life.